Angular velocity/angular acceleration calculator, torque estimator, and combustion state estimator

Abstract

An angular velocity / angular acceleration calculator of the crankshaft in an internal combustion engine includes a crank angle detection device, a crank angle correction device, and an angular velocity / angular acceleration calculation device. The crank angle detection device detects a crank angle in the internal combustion engine and a time at the crank angle. The crank angle correction device corrects the crank angle and the time thus detected to an equiangular crank angle and a time corresponding thereto. The angular velocity / angular acceleration calculation device calculates an angular velocity and an angular acceleration of the crankshaft by converting a function of the time with respect to the crank angle that are corrected by the crank angle correction device so as to be regarded as a periodic function, and utilizing the discrete Fourier transform of the converted function.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to angular velocity / angular acceleration calculators, torque estimators, and combustion state estimators, and particularly relates to an angular velocity / angular acceleration calculator, a torque estimator, and a combustion state estimator for an internal combustion engine.[0003]2. Description of the Background Art[0004]Highly accurate control of an internal combustion engine is effectively realized by measuring a combustion state of the engine and controlling the engine with a measurement result thereof being fed back. For such highly accurate control, it is important to precisely measure the combustion state of the engine. The combustion state of the engine can be measured by measuring an internal pressure of a cylinder with a cylinder internal pressure sensor to calculate a torque, or by estimating a gas pressure torque according to a crank angle sensor signal.[0005]Japanese Patent Appli...

AI Technical Summary

Benefits of technology

[0012]In the torque estimator described above, the angular velocity / angular acceleration calculator accurately calculates an angular velocity and an angular acceleration of the crank. Accordingly, accurately estimated are a gas pressure torque as well as an external torque.

[0014]In the above combustion state estimator according to the present invention, the angular velocity / angular acceleration calculator accurately calculates an angular velocity and an angular acceleration of the crank, so as to accurately estimate the combustion state.

Problems solved by technology

However, problems on durability and cost arise in such a method of measuring an internal pressure of a cylinder with a cylinder internal pressure sensor and calculating a torque.

Therefore, this method is not for calculating an angular acceleration.

Accordingly, the method of Japanese Patent Application Laid-Open No. 2005-61371 is limitedly applicable since a gas pressure torque can be measured only in a case where an external torque excluding a friction torque is obviously equal to zero or in a case where a load torque can be estimated with an additional measurement device such as an inclination sensor.

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